<span>Typed letter from Ambrose Swasey to Charles F., Sr., thanking Brush for sending latest gravitation paper, hoping that Brush will continue to work on the issue and </span><span>present again at next American Philosophical Society meetingCharles F. Brush, Sr., PapersSeries 1: CorrespondenceSubseries 2: Acknowledgments (1921-1929)Box 2Folder 14</span>